Process for the production of cyanocarbonic acid amides



United States Patent Luhowy et al.

MERCAPTOETHY LATION OF AMINES Inventors: Roberta R. Luhowy. Newton;Frank A. Meneghini, Arlington. both of Mass.

Assignee: Polaroid Corporation, Cambridge.

Mass.

Filed: Aug. 21, 1973 Appl. No.: 390,209

Related US. Application Data Continuation-impart of Ser. No. 343.284.March 21. 1973. abandoned.

[ Nov. 11, 1975 [56] References Cited UNITED STATES PATENTS 3.231.6171/1966 James 260/583 EE OTHER PUBLICATIONS Chem. Abst.. Vol. 67. 634343.Chem. Abst. V01. 30. 6008.7 (.1. Gen. Chem). 21, 88-93, (1951).

Prinmr E.\'aminer--Lewis Gotts Assistant Examiner-D. R. PhillipsAttorney, Agent, or Firm-Sybil A. Campbell 5 7 ABSTRACT This inventionrelates to an improved method for the mercaptoethylation of amines andammonia wherein episulfide and amine. or ammonia, are reacted insolution containing silver salt.

22 Claims, No Drawings MERCAPTOETHYLATION OF AMINES CROSS-REFERENCE TORELATED PATENT APPLICATION This application is a continuation-impart ofUS. application Ser. No. 343,284 filed Mar. 21, 1973, now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates to a method of synthesizing B- mercaptoethylamines.

2. Description of the Prior Art B-mercaptoethylamines(Z-aminoethanethiols) and their derivatives have found utility invarious applications, for example, in the rubber industry as disclosedby H. R. Snyder et al., J. Amer. Chem. Soc., 69, 2672 (1947); in thepharmaceutical industry as disclosed by R. 0. Clinton et al., J. Amer.Chem. Soc., 70, 950 (1948) and in Chem. and Eng. News, November 23,I959, pp. 42-43; and in the photographic industry as disclosed in US.Pat. No. 3,221,0l3. B-mercaptoethylamines are also useful in syntheticchemistry as reagents for the preparation of 1,3-sulfur-nitrogencompounds, e.g., thiazolidines, as reported by M. P. Schubert, J. Biol.Chem, 114, 341 (1936).

As discussed by D. D. Reynolds et al., Mech. Reactions Sulfur Cmpds., 5,pp. 103-130 (1970), several different methods have been employed in theproduction of mercaptoethylamines. Of the variety of synthetic routesused to prepare these compounds, one of (A) R NH the most directinvolves the addition of amines to episulfides or episulfide precursors.Although this reaction is general, applying to both aromatic andaliphatic amines, it suffers from the disadvantage that it oftenrequires higher temperatures of 100 to 200C. in sealed tubes and thatthe yields are dependent on solvent polarity. A further disadvantage ofthis reaction is that the product mercaptoethylamines are furthermercaptoethylated on sulfur or nitrogen to give bis-mercaptoe- 5 theproduct.

The present invention is concerned with an improved method ofsynthesizing fi-mercaptoethylamines by the reaction of amines or ammoniaand episulfides which does not require high temperatures of 100C. ormore.

SUMMARY OF THE INVENTION It is, therefore, the primary object of thepresent invention to provide an improved method for the preparation ofmercaptoethylamines.

Other objects of this invention will in part be obvious and will in partappear hereinafter.

The invention accordingly comprises the process involving the severalsteps and the relation and order of one or more of such steps withrespect to each of the others, which are exemplified in the followingdetailed disclosure, and the scope of the application of which will beindicated in the claims.

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the presentinvention, we have found that the mercaptoethylation of ammonia andamines can be carried out near room temperature with equimolar amountsof episulfide and amine or ammonia in aqueous or organic mediacontaining silver salt. The

proposed reaction scheme of the subject method is illustrated below:

The advantages afforded by this method are the mild reaction conditionsinvolved, its general application to ammonia and various primary andsecondary amines, aliphatic and aromatic, and the ease with which theproduct may be separated from unreacted starting material via itssilvercomplex. Moreover, as seen from Table l, the method is equallyapplicable to substituted episulfides including bis-episulfides as wellas ethylene sulfide.

-continued SH NRR (NH Com ound Structure (Z Yield Ex. R R R R by wt.)

With the unsymmetrically substituted episulfides the nals were observedfor the analytically pure aminoethquestion of regiospecificity arises.It is known that unanethiols, l3 and 14. It appeared that for the firsttime symmetrically substituted episulfides suffer nucleothe addition ofamines to unsymmetrically substituted philic attack at the leastsubstituted carbon atom, and episulfides may have given rise to twoisomers. From there are numerous examples of this in the addition of theintegrated values of the methylene signals the isoamines to episulfides.However, the presence of elecmer ratio was about two to one. Indeed, forcompound trophilic reagents is known to lead to appreciable ring 13 wecould resolve the mixture of isomers by fracopening at both carboncenters of such compounds, tional crystallization of the hydrochloridesalts. This i.e., at the most hindered and the least hindered cargavethe major isomer. Chromatography of the mother bon. Moreover, sulfenylchloride additions to olefins liquors gave the other isomer. The nmrspectra of the which are presumed to go through similar episulfonium twoisomers added up to that of the mixture.

ion intermediates also lead to products derived from Control experimentshave shown that the non-silver attack of chloride at both carboncenters. It was theremediated reaction of aniline with isobutylenesulfide fore of interest to see if the incorporation of an electroled toonly one isomer, which in fact, was the major isophile like silver ionresulted in a reversal of the usual mer obtained with silver present.Based on the premise mode of episulfide ring opening by amines. that thenon-assisted reaction led to l,l-dimethyl-2- The direction of ringopening was established by anilinoethanethiol, the silver ion mediatedreaction is comparing the product obtained from equation (A) found tolead to a two to one mixture of l,l-dimethylusing isobutylene sulfideand methyl amine with 1.1- 2-anilinoethanethiol and2,2-dimethyl-2-anilinoethanedimethyl-2-methylaminoethanethiol preparedas shown thiol, respectively. To our knowledge this is the first inequation (B) below: documented example of a non-selective attack of anCH, CH, CH, CH,

NaBH, NaBr (B) CH, CHO NaHS CH cHo+cH,NH SH NHCH Br SH The hydrochloridesalts of both aminoethanethiols had amine on an unsymmetricallysubstituted episulfide. the same ir and nmr spectra, and both disulfide-di- The control experiment also showed that silver ion hydrochloridesalts melted with decomposition at accelerated the rate of reaction,since no reaction be- 268270C. These mercaptoethylamines were contweenaniline and isobutylene sulfide occured for up to verted intothiazolidines by reaction with p-dimethree days at room temperature.thylaminobenzaldehyde and the di-hydrochloride salts Apparently theactivation provided by silver ion in of these two derivatives were shownto be identical by the mercaptoethylation of amines results in apredomiir, nmr and melting point. Thus, the aminoethanethiols nance ofthe same isomer as obtained without silver of the two reactions beingidentical, it was concluded present. Possible roles attributed to silverion in this rethat the direction of episulfide ring opening bymethylaction are that it acts as an electrophile for sulfur reamine isnot changed by the presence of silver ion in sulting in C-S bondweakening, it coordinates to the rethe reaction media. Accordingly, theproduct from the agents to form a kinetically active ternary complex, orsilver ion mediated reaction of isobutylene sulfide and it provides amore favorable free energy for the reacmethylamine was assignedstructure 5; i.e., the isomer tion by forming a stable complex with theproduct. derived from amine attack at the least substituted car- Themethod of the present invention finds general bon atom. By analogymercaptoethylamines of the application in the mercaptoethylation ofammonia and other aliphatic amines, 26, 8 and I0, were assigned ofamines containing at least one replaceable hydrogen structures as shownin Table 1. atom, including monomeric and polymeric amines. WithB-mercaptoethylamines derived from relatively Typical of such amines arethose represented by the non-nucleophilic amines, like aniline, andunsymmetriformula (I), RR,,NH wherein R is selected from alkyl;

cal episulfides, like isobutylene sulfide, the nmr spectra alkylsubstituted with, e.g., alkoxy, N,N-dialkylamino, were quite unusual.Two methyl and two methylene sig- OH, COOR', SO H, and SO NHR'; phenyl',

and phenyl substituted with, e.g., N,N-dialkylamino, -OH, COOR', SO H,SO NHR, alkyl, alkoxy and alkenyl, which alkyl, alkoxy and alkenylgroups may be substituted with, e.g., hydroxy, carboxy and sulfo and Ris selected from hydrogen and the groups enum erated for R. R of theabove COOR' and SO NHR' groups may be hydrogen or alkyl containing 1 tocarbon atoms.

The R and R groups are not limited to a particular number of carbonatoms since the amine need not be soluble in the reaction medium but mayform either a homogenous or heterogeneous solution therewith. Indeed, ithas been found that the subject process is equally applicable to longchain hydrophobic amines as well as methylamine. In the aliphaticamines, the alkyl group and the alkyl portion of the substituted alkylgroups comprising R and R usually contain 1 to 20 carbon atoms but maycontain a greater number of carbon atoms, if desired. The alkoxysubstituent and the dialkyl groups of the amino substituent also maycontain 1 to 20 carbon atoms. In the aromatic amines, the alkyl, alkoxyand alkenyl groups substituted on the phenyl usually contain 1 to 20carbon atoms and the dialkyl groups of the N,N-dialkylamino substituentalso may contain 1 to 20 carbon atoms.

Any episulfide may be employed in the present method. Illustrativeepisulfides are those represented by the formula, (II),

wherein R is selected from hydrogen and alkyl containing l to 20 carbonatoms, and R is selected from hydrogen, alkyl containing 1 to 20 carbonatoms, and the group,

wherein n is an integer l to 4 and R has the same meaning given above.Such compounds are well known and, generally, are prepared by reactingthe corresponding epoxide with potassium thiocyanate in aqueous ordilute alcoholic solutions. The epoxide may be prepared in aconventional manner by reacting an olefin, e.g., l-octene or l-docosenewith a peracid, such as, meta-chloro-perbenzoic acid.

Though for convenience, silver nitrate is usually employed as the silversalt to provide the silver ion in the subject reaction, other silversalts may be employed. For example, silver acetate and silver tosylatehave been employed and found to give the same results as silver nitrate.

Typical of the B-mercaptoethylamines produced in accordance with thepresent invention are the compounds represented by the followingformulae:

( m l Ri/R, (IV) R R, SH NRR" SH NHL,

wherein R, R R and R have the same meaning given in formulae l and IIabove.

In the method of the present invention, the episulfide and ammonia oramine reactants are used in approximately equimolar proportions, thatis, about 1.0 mole of ammonia or amine is reacted with l .0 mole ofepisulfide. The silver salt, for example, silver nitrate may be employedin amounts from a catalytic amount to greater than stoichiometricamounts as based on the episulfide.

Though the subject reaction may be conducted at high temperatures insealed tubes, one of the advantages of the present invention is that thereaction may be carried out at comparatively low temperatures, usuallybetween about l0 and 60C., thereby minimizing the formation of reactionby-products and eliminating the need for sealed tubes with lower boilingreactants, such as, ethylene sulfide. Therefore, the episulfide andamine reactants ordinarily are mixed together at room temperature orthereabouts.

The usual experimental procedure involves the slow addition of asolution of a silver salt to a solution of the amine or ammonia to forman amine-silver ion complex. It may be desirable to use excess aminereactant or a tertiary amine, such as, triethylamine as a protonacceptor, and in aqueous solution, to prevent precipitation of silveroxide. Other proton acceptor, such as, sodium carbonate and sodium acidcarbonate also may be employed. The silver complexation is accompaniedby a mild exotherm. After cooling to room temperature, i.e., about 20C.,a solution of episulfide is slowly added, and the reaction is allowed toproceed without the application of external heat. This addition isusually accompanied by the formation of an insolublesilveraminoethanethiol complex. Since heat is evolved during theaddition of episulfide, it may be desirable to use external coolingmeans to maintain the reaction mixture at the selected temperature,usually room temperature or thereabouts. The reaction mixture is stirreduntil the reaction is complete, about 2 to 15 hours, and the insolublesilver complex isthen treated with H 5 to liberate the aminoethanethioland precipitate out the Ag S. The product may be isolated in a varietyof ways including distillation, or more frequently by conversion to itshydrochloride salt. The amine and episulfide reactants also may be mixedtogether followed by the addition of silver salt but the above procedureis preferred.

As noted above, the reaction may be conducted in aqueous solution or inorganic solution. With ammonia and gaseous amines, for example,methylamine, the reaction is most conveniently carried out in aqueousmedia using commercially available aqueous ammonia cal and methylaminesolutions. With the liquid and solid amines, the reaction isconveniently carried out in an inert organic solvent, though the latteramines also may be used in aqueous reaction medium. Illustrative organicsolvents include N,N-dimethylformamide, dimethylsulfoxide andnitromethane. A solvent found particularly useful in the subjectreaction for obtaining good product yields with both aliphatic andaromatic amines is acetonitrile. The use of this preferred solvent formsthe subject matter of copending application Ser. No. 412,3]4 of LouisLocatell, Jr. and Frank A. Meneghini filed Nov. 2, 1973.

The following Examples are given to further illustrate the presentinvention and are not intended to limit the scope thereof.

EXAMPLE 1 Preparation of decylaminoethanethiol To a stirring solution of15.5 g. (0.153 mol.) of triethylamine in 75 ml. of distilled water wasslowly added a solution of 12 g. (0.071 mol.) of silver nitrate (AgNO in20 ml. of water. A small amount of black silver oxide (Ag O) fomied. Thetemperature was adjusted to 25 C. and 14.5 g. (0.092 mol.) of decylaminewas added. Dropwise addition of g. (0.084 mol.) of ethylene sulfide wasaccompanied by evolution of heat (temperature rose to 47C.) andformation of an insoluble yellow silver-complex. After stirring for 1.5hrs. the silvercomplex was filtered off, washed with distilled water,and suspended in 100 ml. of distilled water. Hydrogen sulfide wasbubbled through the vigorously stirred mixture to liberate the freemercaptoethylamine. The mixture was filtered and the silver sulfide (AgS) precipitate was washed with hot ethanol. The washings were combinedwith the original filtrate and evaporated in vacuo. The residue wastreated with 100 ml. of water and extracted with ether. Solventevaporation led to 16.5 g. (90% by weight yield) of product, n 25 1.4702(lit. n 25 1.4674). Anal. Calcd. for C H NS: C, 66.29; H, 12.52; N,6.44; S, 14.75. Found: C, 66.09; H, 12.38; N, 6.18; S, 14.66.

EXAMPLE 2 Preparation of 1-methyl-2-( 3methoxypropylamino )-ethanethiolUsing the procedure described above 50 g. (0.29 mol.) of AgNO in 60 ml.of water was added to a solution of 63.5 g. (0.71 mol.) ofmethoxypropylamine in 200 ml. of water. While maintaining thetemperature below 30C., 19 g. (0.26 mol.) of propylene sulfide wasslowly added. An oily semisolid separated out. After stirring for 2hours 70% perchloric acid (HCLO was slowly added until no furtherprecipitation occurred. The supernatant was decanted off and the residuewas washed with water until the washings were at pH 7. The freemercaptoethylamine was liberated from its silvercomplex with hydrogensulfide as described in Example 1. Claisen distillation led to 1 g. offore-run, 17 g. (40% by weight yield) of clear liquid distilling at 55C.(0.95 mm), n,, l .4705, and 9 g. of residue. Anal. Calcd. for C-,H NOS:C, 51.48; H, 10.49; N, 8.58; S, 19.64. Found: C, 51.65; H, 10.37; N,8.58; S, 19.67.

EXAMPLE 3 Preparation of l,1-dimethyl-2-( 3-di-n-butylaminopropylamino)-ethanethiol An aqueous (160 ml.) mixture of 34 g. (0.20 mol.) of AgNO-53 g. (0.53 mol. of triethylamine and 35.3 g. (0.19 mol.) ofdi-n-butylaminopropylamine was prepared as in Example 1, and 16.5 g.(0.18 mol.) ofisobutylene sulfide was slowly added to it. During theepisulfide addition the temperature rose to 50C. and the reactionmixture became more viscous. After stirring overnight the freemercaptoethylamine was liberated from its silver-complex with H s.Claisen distillation of the oil residue led to 4 g. of forerundistilling at 1l4123 C. (0.45 mm.), n,,27 1.4644, g. distilling atl23-128C. (0.5 mm), n,,27 1.4666 and 10.5 g. distilling at 128C. (0.45mm), n,,27 1.4666. The yield based on the last two cuts was 40% byweight. Anal.

Calcd. for C, H N S: C, 65.63; H, 12.48; N, 10.20; S, 11.68. Found: C,65.64; H, 12.22; N, 10.34; S, 11.46.

EXAMPLE 4 Preparation of 1 ,1-dimethyl-2-hexadecylammoniumethanethiolperchlorate An aqueous (300 m1.) mixture of 65 g. (0.38 mol.) of AgNO105 g. (1.04 mol.) of triethylamine and 77 g. (0.32 mol.) ofhexadecylamine was made up as in Example 1 and 31.5 g. (0.36 mol.) ofisobutylene sulfide was slowly added. The temperature rose to about 53C.After stirring at room temperature (about 23C.) for 3.5 hrs. 110 g.(0.78 mol.) of 70% HCLO, was added. Within 10 min. the mixtureagglomerated. The supernatant was decanted off and 600 ml. of 50%aqueous ethanol was added. The mercaptoethylamine was liberated from itssilver-complex with H 8, and HC1O (about 30 g.) was added until themixture was below pH 2. After heating on the steam bath to help dissolvethe product, the mixture was filtered. The Ag S precipitate was treatedwith ethanol, heated and again filtered. Upon addition of water to thecombined filtrates a white solid came out of solution which was driedover P 0 The yield of crude product was 84 g. (61% by weight yield).Recrystallization from hexane-methanol and twice from ethanol gave thedisulfide salt: melting range 224-228C. dee. Anal. Calcd. for C ,,H N SC1 O C, 55.98; H, 10.10; N, 3.27; S, 7.47; Cl, 8.26. Found: C, 56.38; H,10.26; N, 3.59; S, 7.61; Cl, 8.02.

EXAMPLE 5 An aqueous (120 ml.) mixture of 88.5 g. (0.52 mol.) of AgNOand 163 g. (2.10 mol.) of methylamine was made up as in Example 1 and44.5 g. (0.51 mol.) of isobutylene sulfide was slowly added whilemaintaining the temperature below 25C. Toward the end of the episulfideaddition a yellow solid precipitated out which congealed after min. ofstirring. The supernatant was decanted off and the residue was washedrepeatedly with water to remove excess methylamine. Aqueous HCl wasadded and the mercaptoethylamine was liberated from its silver-complexwith H 8. The Ag S was filtered off and the filtrate was evaporated todryness in vacuo. The residue was dissolved in hot chloroform, driedwith magnesium sulfate and the solvent was removed under reducedpressure. The resulting residue was triturated with ether to yield 62 g.(79% by weight yield) of white solid which was crystallized fromdioxane-methanol; melting range 222224C. dec.; ir (KBr) 2950, 1457 (CH),2645, 2490, 2400, 1585 (NHJ), 1415 (CH N 1390, 1365, 1175, 1162 ((CH C);nmr (D 0) 5 1.43 (6,s, C(CH 2.77 (3,s,NCH 3.16 (2,s,CH Anal. Calcd. forC H,,NSCl: C, 38.57; H, 9.06; N, 9.00; S, 20.60. Found: C, 38.73; H,9.35; N, 8.84; S, 20.97.

The fi-mercaptoethylamine prepared in Example 5 above was reacted withp-dimethylaminobenzaldehyde to form2-(p-dimethylaminophenyl)-3.5,5-trimethylthiazolidine-di-hydrochlorideaccording to the following procedure:

A mixture of 2 g. (0.013 mol.) of 1.1-dimethyl-2- methylaminoethanethiolhydrochloride, 1.1 g. (0.013 mol.) of NaHCO and 2 g. (0.013 mol.) ofp-dimethylaminobenzaldehyde in 100 ml. of 95% ethanol was refluxedthrough a Soxhlet extractor containing CaC for an overnight period. TheNaCl was filtered off and the filtrate was evaporated to dryness. Theresulting oil was dissolved in absolute ethanol and the solution wasmade acidic with gaseous HCI. Upon cooling a yellow solid came out ofsolution which was recrystallized from ethanol-ether to give 2.2 g. (48%by weight yield) of white product: melting range 2,162l7C. dec.; ir(KBr) 3000, 2940, 2900, 1460, 1137, 827 (CH), 2670-2300 (NH*), 1610,1510 (aromatic); nmr (D 61.77, 1.80 (6, C(CH 2.93 (3, s, NCH 3.40 (6, s,N(ch 3.67 l, A of AB q, J= 12 Hz, CH 4.03 l, B of AB q, .l 12 Hz, CH5.96 (l, s, CH), and an AA BB pattern centered at 7.84 (4, m, C 11 Anal.Calcd. for C H N SCl C, 52.00; H, 7.48; N, 8.66; S, 9.92. Found: C,51.93; H, 7.51; N, 8.65; S, 9.78.

EXAMPLE 6 Preparation of l-methyl-2-methylaminoethanethiol hydrochlorideA solution of 59.6 g. (0.35 mol.) of AgNO dissolved in 100 ml. of waterwas slowly added over a 45 minute period to 110.5 g. (1.42 mol.) of 40%methylamine while stirring in an ice bath. The temperature was 1 1C.While maintaining this temperature, 26 g. (0.35 mol.) of propylenesulfide was added dropwise via a dropping funnel over a 20 minuteperiod. The reaction mixture turned cloudy and then small yellowaggregates formed. As more propylene sulfide was added, the mixturebecame a thick slurry. No coagulation or cogealing was noted. Themixture was allowed to stir at room temperature for about 2 hours (thetemperature reached was about 28C.), and then was filtered and theprecipitate washed with water to removed excess methylamine. Theprecipitate was transferred to a 3- neck flask and suspended inapproximately 100 ml. of water. The resulting mixture was stirred and 28ml. of aqueous l-lCl was added (pH of 1.0). H 8 was bubbled through themixture for about 3 hours and then the mixture was filtered and thefiltrate evaporated to remove water. The residue obtained was dissolvedin methanol and magnesium sulfate was added. The methanol solution wasfiltered, evaporated and the residue treated with hot dioxane/methanol.The first precipitate did not show a methyl peak on nmr. The filtratewas evaporated to dryness and treated with hot dioxane/ether. Thedioxane/ether was evaporated to dryness and upon cooling, a whitecrystallize wax residue was obtained which, when treated with methylenechloride, gave a fine white precipitate. The white precipitate (5.0 g.)was collected by filtration and the filtrate was treated with ether inan ice bath. Approximately 20.0 g. of a hygroscopic precipitate wascollected having an nmr with a methyl peak similar to the whiteprecipitate. The remaining filtrate was evaporated to dryness andyielded an oil (about 7.0 g.) with an nmr similar to those of the twoprecipitates.

The two precipitates and oil comprising the title compound were combinedand reacted with p-dimethylaminobenzaldehyde following the proceduregiven in Example to give 2-(p-dimethylaminophenyl)-3,5-dimethylthiazolidine-dihydrochloride, which was recovered inanalytically pure form.

EXAMPLE 7 Preparation of methylaminoethanethiol An aqueous ml.) mixtureof 140 g. (0.86 mol.) of AgNO and 100 g. (1.29 mol.) of 40% methylaminewas prepared as in Example 1, and 25.6 g. (0.43 mol.) of ethylenesulfide was slowly added to the mixture over a 45 minute period. Thetemperature rose to about 57C. After stirring at room temperatureovernight, the supernatant was decanted off, and the solid remaining waswashed with water to remove excess methylamine. The solid was thensuspended in distilled water, and H S was bubbled through the mixturefor about 3 hours. The mixture was filtered and the filtrate wasstripped to give 10 g. of a yellow oil. TLC from ethyl acetate showedthree spots.

The yellow oil comprising the title compound was reacted withp-dimethylaminobenzaldehyde following the procedure given in Example 5above to yield 2-(pdimethylaminophenyl 3-methylthiazolidine-di-hydrochloride, which was recovered inanalytically pure form.

EXAMPLE 8 Preparation of l l -dimethyl-2-amino-ethanethiol hydrochloride The title compound was prepared following the procedure ofExample 5 above using as the reactants, aqueous ammonia and isobutylenesulfide, and was obtained in 55% by weight yield.

The title compound was reacted with p-dimethylaminobenzaldehydefollowing the procedure outlined in Example 5 above and gave thecorresponding, thiazolidine, 2-(p-dimethylaminophenyl )-5,S-dimethylthiazolidine-di-hydrochloride.

EXAMPLE 9 Preparation of Z-(di-n-butylamino)-ethanethiol hydrochloride26 g. (0.2 mole) of di-n-butylamine was added slowly with stirring to 34g. (0.2 mole) of silver nitrate dissolved in about 200 cc. ofacetonitrile. 12 g. (0.2 mole) of ethylene sulfide dissolved in 25 cc.of acetonitrile was slowly added over about 20 minutes. The temperaturewas maintained between 2030C. with external cooling. The mixture wasallowed to stand at room temperature (about 20C.) for 15 hours. The gelformed after standing was triturated with water and a solid formed. Thesolid was filtered off and suspended in ethanol. H 8 was bubbled throughthe suspension and the Ag S that formed was filtered off. The filtratewas evaporated in vacuuo. The resulting oil was partitioned between anaqueous sodium carbonate solution and ether. The ether was dried andevaporated leaving an oil. The oil was dissolved in ethanol,hydrochloric acid was bubbled in, and a solid precipitated out. Thesolid was recrystallized from ethanol to give the title compound in 75%by weight yield, melting range 1l2.5l C.

EXAMPLE 10 Preparation of l,8-di(methylamino)-2,7-di(mercapto) octanedihydrochloride An aqueous (240 cc) solution of 51.0 g. (0.3 mole) ofAgNO and 98 g. (1.2 moles) of 40% methylamine was made up as in Example1 and 19.2 g. (0.110 mole) of l,7-octadiene-bis-episulfide was slowlyadded while maintaining the temperature below 25C. with externalcooling. Toward the end of the bis-episulfide addition, a yellow solidprecipitated out which congealed after 45 minutes of stirring. Stirringwas continued overnight. The supernatant was decanted and the coagulatedprecipitate was washed with water, made acidic with cone. HCl, and H 8was bubbled into the acidic suspension for two hours. The Ag Sprecipitate formed was filtered and the filtrate evaporated to dryness.An oily solid remained. This oil was triturated with ethyl acetate and asmall amount of ethanol was added to precipitate a first fraction of 4.0g. of a white solid, m.p. 191-193C. comprising the title compound. Asecond fraction of 6.0 g. and a third fraction of 10.0 g. was obtainedin the same manner. The total yield of title compound was 30% by weight.

EXAMPLE 11 Preparation of 2-anilinoethanethio1 To 34 g. (0.2 mole) ofsilver nitrate in 250 ml. of acetonitrile was added 186 g. (0.2 mole) ofaniline in 250 ml. of acetonitrile. To the rapidly stirred solution wasadded 12 g. (0.2 mole) of ethylene sulfide in 25 ml. of acetonitrile. Noimmediate reaction was noted. After 25 min., when approximatelytwo-thirds of the ethylene sulfide solution had been added, a yellowprecipitate began to form accompanied by an exotherm. The temperaturerose to 27C., and the solution was cooled to 20C. Stirring was continuedat 20C. for 24 hours. Most of the acetonitrile was decanted andevaporated. The residue of the evaporated acetonitrile plus 500 ml. ofethanol was added to the flask containing the precipitate remainingafter decanting the solvent. H was bubbled through the suspension forabout 1.5 hours. The Ag S precipitate formed was filtered through Celiteand the filtrate was evaporated. The residue was distilled --a first cutat +C. and 4 mm and a second cut at 87C. and 0.35 mm. The title compoundwas recovered in 45% by weight yield.

EXAMPLE 12 Preparation of 2-N-methylanilino ethanethiol To 34 g. (0.2mole) of silver nitrate in 50 cc. of acetonitrile was added 10.7 g. (0.1mole) of N-methyl aniline in 25 cc. of acetonitrile and 8.6 g. (0.1mole) of sodium bicarbonate. Then 6.0 g. (0.1 mole) of ethylene sulfidein cc. of acetonitrile was slowly added. The temperature was maintainedbetween -26C. with external cooling. A white precipitate fonned in thepurple solution, and the solution was allowed to stir at roomtemperature for 1.5 hours. The acetonitrile was evaporated in vacuuo.The residue was suspended in ethanol, and H 5 was bubbled through thesuspension for 1.5 hours. The Ag S precipitate formed was filtered, andthe filtrate was evaporated in vacuuo. The resulting oil was partitionedbetween an aqueous solution of NaHCO and acetonitrile. The acetonitrileextract was dried and evaporated. The residue was distilled giving thetitle compound in a 50% by weight yield.

EXAMPLE 13 Preparation of 1,1-dimethyl- 2-anilinoethanethiol 34 g. (0.2mole) of silver nitrate was dissolved in 50 cc. of acetonitrile. To thissolution was added 18.6 g. (0.2 mole) of aniline, 50 cc. of acetonitrileand 20.24 g.

(0.2 mole) of triethylamine. The mixture was a black color. 17.6 g. (0.2mole) of isobutylene sulfide was then slowly added. The temperature wasmaintained between 2030C. After standing at room temperature for 15hours, the mixture was evaporated in vacuuo. The residue was suspendedin ethanol, and H 5 was bubbled into the suspension for 1.5 hours. TheAg S formed was filtered, and the filtrate was evaporated in vacuuo. Theresidue was partitioned between water and acetonitrile. The acetonitrileportion was washed twice with water and then dried and evaporated. TLCshowed one major sport and several minor ones. The mixture waschromatographed on fluorisil with acetonitrile as eluent. The materialcorresponding to the major spot was collected, the eluent evaporated offand the residue was distilled to give the title compound in 62% byweight yield.

EXAMPLE 14 Preparation of 1 ,l -dimethyl-2-p-vinylanilino ethanethiol35.7 g. (0.3 mole) of vinylaniline in 200 ml. of acetonitrile and sodiumbicarbonate (0.33 mole) were added to a solution of 15.0 g. (0.3 mole)of silver nitrate in 250 ml. of acetonitrile. 26.4 g. (0.3 mole) ofisobutylene sulfide in 50 m1. of acetonitrile was then slowly added. Thetemperature reached about 55C. After addition was complete, the mixturewas allowed to stir 1.5 hours at room temperature. The yellow solid thatformed was broken up, the acetonitrile removed by filtration and thesolid washed with 500 ml. of ethanol and filtered. The solid was thensuspended in 500 ml. of ethanol, and H 5 was bubbled into the suspensionfor about 2 hours. The Ag S precipitate that formed was removed byfiltration and the filtrate evaporated in vacuuo. The residue wasdistilled to give the title compound in 35% by weight yield.

EXAMPLE 15 Preparation of l ,1 -dimethyl-2-oc tadecylaminoethanethiolhydrochloride The title compound was prepared following the procedure ofExample 5 except that octadecylamine was substituted for methylamine.

EXAMPLE 16 Ppreparation of l ,l-dimethyl-2-B-hydroxy ethylaminocthanethiol The title compound was prepared following the procedureof Example 14 employing B-hydroxyethylamine and isobutylene sulfide asthe reactants.

EXAMPLE 1? Preparation of 2-p- G-hydroxyethylanilinoethanethiol Thetitle compound was prepared following the procedure of Example 14employing p-B-hydroxyethylaniline and ethylene sulfide as the reactants.

EXAMPLE 1 8 Preparation of l ,1dimethyl-2-p-methylsulfonamidoanilinoethanethiol The title compound wasprepared following the procedure of Example 14 employingp-methylsulfonamidoaniline and isobutylene sulfide as the retro tants.

EXAMPLE 19 Preparation of l l-dimethyl-2-p-carbethoxymethoxyanilinoethanethiol The title compound wasprepared following the procedure of Example 14 usingp-aminophenoxyethylacetate and isobutylene sulfide as the reactants.

Examples 7 and I were repeated using acetonitrile as the solvent bybubbling gaseous methyl amine into a solution of silver nitrate inacetonitrile to give substantially the same results as reported above.Example 11 also was repeated using different silver salts, namely,silver acetate and again with silver tosylate to give substantially thesame results reported above.

The l ,1-dimethyl-2-methylaminoethanethiol hydrochloride made forcomparative purposes by reduction of mercaptoisobutyraldehyde Schiffbase (equation B above) was prepared as follows.

A solution of 2.5 g. NaSH.Xl-l O in 10 ml. of methanol was added to 4 g.(0.026 mol.) of bromoisobutyraldehyde in 20 ml. of methanol. Afterstanding l.5 hrs., 2.5 g. (0.032 mol.) of 40% methylamine and 20 ml. ofacetic acid were added and the mixture was stirred for 5 min. Whilecooling, ml. of acetic acid and 8.5 g. (0.22 mol.) of NaBH wasalternately added in small portions. The mixture was stirred for 1.5hrs. and water was added to destroy the excess NaBH Methanol and HClwere added and the mixture was distilled until the distillate no longershowed a green flame test for boron. The remainder of the solvent wasremoved under reduced pressure and the residue was extracted with CHCIThe CHCl was removed under vacuum and the residue was triturated withether to give 1 g. (25% by weight yield) of crude product which wasrecrystallized from dioxane-methanol.

Infrared spectra reported above were taken on a Perkin-Elmer Model 421spectrophotometer. Nuclear magnetic resonance spectra were obtained witha Varian A-60 spectrometer. Melting points (melting ranges) areuncorrected and were taken in sealed capillaries on a Mel-Temp.

As noted above, the subject method affords many advantages. For example,it has general application in the synthesis of aminoethanethiolsstarting with ammonia or any amine having at least one replaceablehydrogen atom, i.e., any primary or secondary aliphatic or aromaticamine, and any episulfide, i.e., unsubstituted or substitutedepisulfide. Stoichiometric concentrations of amines may be employedwithout loss of yield to higher mercaptoethylated products. The limitingamount of amine that may be used, besides being economical, allowsgreater ease of work-up. Though the subject reaction may be carried outover a temperature range of about 10 C. to 200 C., higher temperaturesof 100 C. or more are unnecessary. The reaction may be convenientlyconducted at room temperature or thereabouts. Such mild reactionconditions allow the synthesis of aminoethanethiols with relativelysensitive functional 14 groups, and relatively non-nucleophilic amineslike aniline may be readily reacted with sterically hinderedepisulfides, e.g., gem-disubstituted episulfide.

Since certain changes may be made in the above pro- 5 cess withoutdeparting from the scope of the invention herein involved, it isintended that all matter contained in the above description shall beinterpreted as illustrative and not in a limiting sense.

What is claimed is:

l. A method which comprises reacting (a) an episulfide and (b) ammoniaor an amine having at least one replaceable hydrogen atom insubstantially equimolar proportions in solution containing silver saltat a temperature between l0 and C. to form the silver complex of thecorresponding B-mercaptoethylamine.

2. A method as defined in claim 1 wherein said solution is aqueoussolution.

3. A method as defined in claim 1 wherein said silver salt is silvernitrate.

4. A method as defined in claim 1 wherein said silver salt is silveracetate.

5. A method as defined in claim 1 wherein said silver salt is silvertosylate.

6. A method as defined in claim 1 wherein said amine is methylamine.

7. A method as defined in claim 1 wherein said amine is octadecylamine.

8. A method as defined in claim 1 wherein said amine ismethoxypropylamine.

9. A method as defined in claim 1 wherein said amine isdi-n-butylaminopropylamine.

10. A method as defined in claim amine is di-n-butylamine.

11. A method as defined in claim amine is aniline.

12. A method as defined in claim 1 amine is p-vinyl-aniline.

13. A method as defined in claim 1 amine is p-B-hydroxyethylaniline.

14. A method as defined in claim 1 amine is p-methylsulfonamidoaniline.

15. A method as defined in claim 1 amine is p-carbethoxymethoxyaniline.

16. A method as defined in claim 1 amine is B-hydroxyethylamine.

17. A method as defined in claim amine is N-methylaniline.

18. A method as defined in claim 1 wherein said episulfide is ethylenesulfide.

19. A method as defined in claim 1 wherein said episulfide is propylenesulfide.

20. A method as defined in claim I wherein said episulfide isisobutylene sulfide.

21. A method as defined in claim 1 wherein said episulfide isl,7-octadiene-bis-episulfide.

22. A method as defined in claim 1 which includes the additional step oftreating said silver complex with hydrogen sulfide to liberate theB-mercaptoethylamine therefrom.

1 wherein said 1 wherein said wherein said wherein said wherein saidwherein said wherein said 1 wherein said

1. A PROCESS FOR THE PRODUCTION OF CYANOCID AMIDES FROM DINITRILESHAVING THE FORMULA